The progress in quantitative evaluation of callus during distraction osteogenesis.

The manual monitoring of callus with digital radiography (X-ray) is the primary bone healing evaluation, assessing the number of bridged callus formations. However, this method is subjective and nonquantitative. Recently, several quantitative monitoring methods, which could assess the recovery of the structure and biomechanical properties of the callus at different stages and the process of bone healing, have been extensively investigated. These methods could reflect the bone mineral content (BMC), bone mineral density (BMD), stiffness, callus and bone metabolism at the site of bone lengthening. In this review, we comprehensively summarized the latest techniques for evaluating bone healing during distraction osteogenesis (DO): 1) digital radiography; 2) dual-energy X-ray scanning; 3) ultrasound; 4) quantitative computed tomography; 5) biomechanical evaluation; and 6) biochemical markers. This evidence will provide novel and significant information for evaluating bone healing during DO in the future.

A comparative study of bone union and nonunion during distraction osteogenesis.

BACKGROUND: The clinical characteristics of bone nonunion during distraction osteogenesis (DO) were rarely discussed. This study was employed to specify the difference between bone union and nonunion during DO. METHODS: The patients with bone lengthening were recruited in our study. The bone union cases indicated the ones that remove the external fixator successfully, whereas the bone nonunion represented the bridging callus did not appear even after 9 months (an absence of bridging callus for at least three out of four cortices on plain radiographs) that needs autogenous bone transplantation. The differences in the pixel value ratio (PVR) growth of regenerated callus, lengthening index (LI), healing index (HI), external fixation index (EFI) and blood biochemical indexes between bone union and nonunion were analyzed. RESULTS: A total of 8 bone nonunion and 27 bone union subjects were included in this study. The PVR growth in bone nonunion was significantly lower than that in bone union (0.19 ± 0.06 vs. 0.32 ± 0.16, P = 0.048). Interestingly, the HI and EFI in bone nonunion was significantly higher than that in bone union (62.0 ± 31.4 vs. 37.0 ± 27.4, P = 0.036; 75.0 ± 30.9 vs. 49.9 ± 16.1, P = 0.006). However, no significant difference with regard to LI was identified (0.76 ± 0.52 vs. 0.77 ± 0.32, P = 0.976). Moreover, the circulating level of urea and lymphocyte count in bone union was significantly lower than that in bone nonunion (4.31 ± 1.05 vs. 5.17 ± 1.06, P = 0.049; 2.08 ± 0.67 vs. 2.73 ± 0.54, P = 0.018). On the contrary, the circulating level of magnesium in bone union was significantly higher than that in bone nonunion (0.87 ± 0.07 vs. 0.80 ± 0.07, P = 0.014). CONCLUSION: Compared to the bone union, the PVR growth was significantly lower, whereas the HI and EFI was significantly higher in the bone nonunion. Moreover, the circulating level of urea, magnesium and lymphocyte count was also different between these two. Therefore, the PVR, HI and EFI seems to be reliable and sensitive indicators to reflect the bone nonunion during DO, which might be considered in bone lengthening. Further prospective studies are still needed to elaborate the concerned issues.

Functional and transcriptomic analyses of the NF-Y family provide insights into the defense mechanisms of honeybees under adverse circumstances.

As predominant pollinators, honeybees are important for crop production and terrestrial ecosystems. Recently, various environmental stresses have led to large declines in honeybee populations in many regions. The ability of honeybees to respond to these stresses is critical for their survival. However, the details of the stress defense mechanisms of honeybees have remained elusive. Here, we found that the Nuclear Factor Y (NF-Y) family (containing NF-YA, NF-YB, and NF-YC) is a novel stress mediator family that regulates honeybee environmental stress resistance. NF-YA localized in the nucleus, NF-YB accumulated in the cytoplasm, and NF-YC presented in both the nucleus and cytoplasm. NF-YC interacted with NF-YA and NF-YB in vitro and in vivo, and the nuclear import of NF-YB relied on its interaction with NF-YC. We further found that the expression of NF-Y was induced under multiple stress conditions. In addition, NF-Y regulated many stress responses and antioxidant genes at the transcriptome-wide level, and knockdown of NF-Y repressed the expression of stress-inducible genes, particularly LOC108003540 and LOC107994062, under adverse circumstances. Silencing NF-Y lowered honeybee stress resistance by reducing total antioxidant capacity and enhancing oxidative impairment. Collectively, these results indicate that NF-Y plays important roles in stress responses. Our study sheds light on the underlying defense mechanisms of honeybees under environmental stress.

Scaffold protein GhMORG1 enhances the resistance of cotton to Fusarium oxysporum by facilitating the MKK6-MPK4 cascade.

In eukaryotes, MAPK scaffold proteins are crucial for regulating the function of MAPK cascades. However, only a few MAPK scaffold proteins have been reported in plants, and the molecular mechanism through which scaffold proteins regulate the function of the MAPK cascade remains poorly understood. Here, we identified GhMORG1, a GhMKK6-GhMPK4 cascade scaffold protein that positively regulates the resistance of cotton to Fusarium oxysporum. GhMORG1 interacted with GhMKK6 and GhMPK4, and the overexpression of GhMORG1 in cotton protoplasts dramatically increased the activity of the GhMKK6-GhMPK4 cascade. Quantitative phosphoproteomics was used to clarify the mechanism of GhMORG1 in regulating disease resistance, and thirty-two proteins were considered as the putative substrates of the GhMORG1-dependent GhMKK6-GhMPK4 cascade. These putative substrates were involved in multiple disease resistance processes, such as cellular amino acid metabolic processes, calcium ion binding and RNA binding. The kinase assays verified that most of the putative substrates were phosphorylated by the GhMKK6-GhMPK4 cascade. For functional analysis, nine putative substrates were silenced in cotton, respectively. The resistance of cotton to F. oxysporum was decreased in the substrate-silenced cottons. These results suggest that GhMORG1 regulates several different disease resistance processes by facilitating the phosphorylation of GhMKK6-GhMPK4 cascade substrates. Taken together, these findings reveal a new plant MAPK scaffold protein and provide insights into the mechanism of plant resistance to pathogens.

Short-term clinical effect of 3D printing techniques on the correction of complex malformations.

BACKGROUND: To explore the clinical effects of 3D printing techniques on the correction of complex malformation. METHOD: A computed tomography (CT) scan was used to collect data on malformations of patients and the orthopedic plan was made by virtual manipulation of the reality before surgery. The results of the virtual orthopedics were compared with the expected results. A guide plate for osteotomy was also utilized when necessary. The actual operation was carried out according to the plan. RESULTS: The average age of the 11 patients was 19.09 years (19.09 ± 6.93 years) and the average follow-up was 16 months (16 ± 15.11 months). The symptoms were obviously improved. The preoperative World Health Organization Disability Assessment Schedule (WHODAS 2.0) score, modified Barthel index and Functional Independence Measure (FIM) score in patients were 70.45 ± 15.75, 96.55 ± 3.78 and 121.36 ± 4.15, respectively and correspondingly 53 ± 12.75, 98.82 ± 1.66 and 123.82 ± 4.60 after surgery, respectively. There were significant differences before and after surgery (P < 0.05). CONCLUSION: The use of 3D printing technology can provide intuitive and accurate help for the correction of complex limb malformations and greatly facilitates the communication between doctors and patients. The FIM score is suitable for the evaluation of the curative effect before and after the treatment of patients with complex malformations.

Demographic inference under the coalescent in a spatial continuum.

Understanding population dynamics from the analysis of molecular and spatial data requires sound statistical modeling. Current approaches assume that populations are naturally partitioned into discrete demes, thereby failing to be relevant in cases where individuals are scattered on a spatial continuum. Other models predict the formation of increasingly tight clusters of individuals in space, which, again, conflicts with biological evidence. Building on recent theoretical work, we introduce a new genealogy-based inference framework that alleviates these issues. This approach effectively implements a stochastic model in which the distribution of individuals is homogeneous and stationary, thereby providing a relevant null model for the fluctuation of genetic diversity in time and space. Importantly, the spatial density of individuals in a population and their range of dispersal during the course of evolution are two parameters that can be inferred separately with this method. The validity of the new inference framework is confirmed with extensive simulations and the analysis of influenza sequences collected over five seasons in the USA.

A systematic review of matrix metalloproteinase 9 as a biomarker of survival in patients with osteosarcoma.

Matrix metalloproteinase 9 (MMP-9) plays an important role in the progression of several types of cancer by increasing tumor growth, migration, invasion, and metastasis and is associated with poor disease prognosis. The possible prognostic value of MMP-9 in osteosarcoma has also been examined, but due to inconsistent results between studies, it has not been possible to draw firm conclusions. To clarify this issue, we conducted a meta-analysis of published studies to provide a comprehensive evaluation of the effect of high MMP-9 expression on the survival outcomes of osteosarcoma patients. Seven studies with a total of 339 patients with osteosarcoma were examined. The pooled odds ratio (OR) with corresponding 95 % confidence interval (95 % CI) was calculated to evaluate the effect of MMP-9 expression on overall survival. Meta-analysis showed that patients with high MMP-9 expression were significantly associated with lower overall survival when compared to their counterparts with low or undetectable MMP-9 expression (OR=6.13, 95 % CI 3.45-10.89, P<0.001). Sensitivity analysis suggested the pooled OR was stable and not significantly changed when a single study was removed. The results from the systematic review and meta-analysis show that MMP-9 is an effective biomarker for predicting survival of patients with osteosarcoma.

The impact of HIV treatment as prevention in the presence of other prevention strategies: lessons learned from a review of mathematical models set in resource-rich countries.

OBJECTIVE: We aimed to assess the potential prevention benefits of HIV treatment as prevention (TasP) in resource-rich countries and examine the potential interactions between TasP and other prevention strategies by reviewing mathematical models of TasP. METHOD: Multiple databases were searched for mathematical models published in the previous 5 years (from July 2007 to July 2012). The nine models located were set in Canada, Australia and the United States. RESULTS: These models' predictions suggested that the impact of expanding treatment rates on expected new infections could range widely, from no decrease to a decrease of 76%, depending on the time horizon, assumptions and the form of TasP modeled. Increased testing, reducing sexually transmitted infections and reducing risky practices were also predicted to be important strategies for decreasing expected new infections. Sensitivity analysis suggests that current uncertainties such as the effectiveness of highly active antiretroviral therapy outside of heterosexual transmission, less than ideal adherence, and risk compensation, could impact on the success of TasP at the population level. CONCLUSION: The results from large scale pilots and community randomized controlled trials will be useful in demonstrating how well this prevention approach works in real world settings, and in identifying the factors that are needed to support its effectiveness.

Phase behavior of colloidal nanoparticles and their enhancement effect on the rheological properties of polymer solutions and gels.

The interaction between nanoparticles and polymers has been of great interest in colloidal theory and novel materials. For example, the properties of polyacrylamide solutions and gels, which are usually used for conformance control and water shut-off in oilfields, can be improved with the addition of nanoparticles. This underlying mechanism and its applicability are investigated in this paper. A strong relationship between the phase behaviors of nanoparticles in polymer solutions and their enhancement effect on the rheology of the nanocomposite polymer solutions and gels was observed. Experiment results showed that the stability of nanoparticles was dependent on several factors, including pH, salinity, and polymer type. At neutral pH conditions, the tendency of the aggregation of nanoparticles was strengthened upon increasing the salinity, polymer concentration, and electronegativity of the polymers. Rheological measurements showed that nanoparticles could improve the viscosity of polymer solutions or the fracture stress of gels only if nanoparticles were aggregated in the corresponding systems. In addition, these rheological parameters significantly increased with increasing salinity and nanoparticle concentration. As a result, the mobility ratio of polymer solutions may be increased several times by the addition of nanoparticles. Referring to the gels, their rupture pressure gradient in the ideal model was also found to increase with nanoparticle concentration. In particular, if the nanoparticle concentration was sufficiently high (reaching 2%), the formed gels would not be destroyed by the injected water, but rather functionally act as a porous medium for permeation.

Prognostic value and therapeutic potential of IAP family in head and neck squamous cell carcinoma.

Head and neck squamous cell carcinoma (HNSCC) ranks as the eighth most prevalent malignancy globally and has the eighth greatest fatality rate when compared to all other forms of cancer. The inhibitor of apoptosis protein (IAP) family comprises a collection of apoptosis-negative modulators characterized by at least one single baculovirus IAP repeat (BIR) domain in its N-terminal region. While the involvement of the IAP family is associated with the initiation and progression of numerous tumours, its specific role in HNSCC remains poorly understood. Thus, this study aimed to comprehensively examine changes in gene expression, immunomodulatory effects, prognosis, and functional enrichment of HNSCC utilising bioinformatics analysis. Elevated levels of distinct IAP family members were observed to varying degrees in HNSCC, with high BIRC2 expression indicating a worse prognosis. Additionally, Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes (KEGG) were used to probe the enrichment of gene expression and biological processes related to the IAP family in HNSCC. The infiltration levels of immune cells were shown to be strongly associated with the IAP gene expression, as determined by subsequent analysis. Hence, BIRC2 could be an effective immunotherapy target for HNSCC. Collectively, novel knowledge of the biological roles and prognostic implications of IAP family members in HNSCC is presented in this study.

Exosomal non-coding RNAs in colorectal cancer metastasis.

Colorectal cancer (CRC) is a type of gastrointestinal cancer with high morbidity and mortality rates, and is often accompanied by distant metastases. Metastasis is a major cause of shortened survival time and poor treatment outcomes for patients with CRC. However, the molecular mechanisms underlying the metastasis of CRC remain unclear. Exosomes are a class of small extracellular vesicles that originate from almost all human cells and can transmit biological information (e.g., nucleic acids, lipids, proteins, and metabolites) from secretory cells to target recipient cells. Recent studies have revealed that non-coding RNAs (ncRNAs) can be released by exosomes into the tumour microenvironment or specific tissues, and play a pivotal role in tumorigenesis by regulating a series of key molecules or signalling pathways, particularly those involved in tumour metastasis. Exosomal ncRNAs have potential as novel therapeutic targets for CRC metastasis, and can also be used as liquid biopsy biomarkers because of their specificity and sensitivity. Therefore, further investigations into the biological function and clinical value of exosomal ncRNAs will be of great value for the prevention, early diagnosis, and treatment of CRC metastasis.

Bibliometric and visual analysis of trends in tenosynovitis research from 1999 to 2021.

BACKGROUND: Tenosynovitis is an acute or chronic inflammatory reaction of the tendon/tendon sheath. The purpose of this study is to summarize the current status, hotspots, and development trends in tenosynovitis related research. METHODS: Data on tenosynovitis from 1999 to 2021 were identified from the Web of Science core collection (WoSCC) database and analyzed using bibliometric software. CiteSpace was utilized to identify the top 25 references with the strongest citation bursts, the top 25 keywords with the strongest citation bursts, the dual-map overlay of journals, and a timeline of keywords. VOSviewer was utilized to conduct co-citation, academic collaboration, and keyword analysis. Microsoft Excel was used to draw relevant charts. RESULTS: A total of 4,740 publications were collected in this study. The United States ranked first in terms of the H-index, total citations, and total number of publications. The University of California System, University of London, and UDICE-French Research Universities were the major contributing institutions to tenosynovitis research. The Journal of Hand Surgery-American Volume, Skeletal Radiology, and American Journal of Sports Medicine were the main publishing channels for tenosynovitis-related articles. Moreover, Maffulli, N., Van der Helm-van Mil, Annette H.M., Ostergaard, M. were major contributing authors to tenosynovitis research. Finally, research on nonsurgical treatment for tenosynovitis appears to be a future hot spot. CONCLUSION: Overall, the number of publications on tenosynovitis grew over the 1999-2021 period. Our study summarized the research status and global trends of tenosynovitis from multiple angles (i.e., countries, institutions, authors, publications). These considerations are helpful to better understand the research hotspots and development trends in the field.

The NT5DC family: expression profile and prognostic value in pancreatic adenocarcinoma.

Pancreatic adenocarcinoma (PAAD) is a malignant tumor with high morbidity and mortality rates. The NT5DC family is an evolutionarily-conserved family of 5'-nucleosidases that catalyze the intracellular hydrolysis of nucleotides. Although the NT5DC family has been linked to the initiation and growth of several cancers, its function in PAAD remains unclear. A series of bioinformatic analyses was used to ascertain the expression, prognosis, gene changes, functional enrichment, and immune regulatory functions of the NT5DC family in PAAD. NT5C2 and NT5DC1/2 mRNA and protein levels are increased in PAAD. Furthermore, the high mRNA expressions of NT5C2, NT5DC2, and NT5DC4 indicate a poor prognosis in patients with PAAD. The enrichment of biological processes and gene expression in the NT5DC family in PAAD were investigated using Kyoto Encyclopedia of Genes and Genomes and Gene Ontology analyses. Further investigations into immune infiltration revealed a close relationship between NT5DC gene expression and immune cell infiltration. These findings provide new insights into the biological function and prognostic value of the NT5DC gene family in PAAD.

Knowledge Mapping of Global Status and Trends for Thromboangiitis Obliterans: A Bibliometrics and Visual Analysis.

Objective: Thromboangiitis obliterans (TAO) is a segmental nonatherosclerotic inflammatory vascular disease characterized by recurrent progressive inflammatory reactions and thrombosis in the small and medium-sized arteries and veins of the extremities. However, there are few bibliometric studies on TAO. Therefore, this study was employed to generalize the research status, hotspots and development trends of TAO-related research. Methods: The data from 1999 to 2022 were collected from the Web of Science core collection database, and analyzed through bibliometrics software. VOSviewer was utilized to carry out academic collaboration between different countries/regions, institutions, and authors, visualization map of co-cited authors, journals, reference, and co-occurring keywords. CiteSpace was used to analyze the dual-map of journals, keyword bursts, and timeline of keywords. Bar and pie charts in this study were statistically analyzed and graphed through Microsoft Excel 2021. Scimago Graphica was applied to map the academic collaboration between different countries/regions. Results: A total of 553 literatures were involved in this study. Japan at the leading global position not only in the number of publications, but also total citations, average citations and H-index. Institution with the major contribution to TAO research is Mashhad University of Medical Sciences, and Nagoya University. Annals of Vascular Surgery, Angiology, Journal of Vascular Surgery are the main publication channel for articles related to TAO. Fazeli, B., Iwai, T., and Kihara, Y. are major contributors in this field. The studies on TAO keywords could be grouped into four clusters: Etiology, Mechanism, Cell therapy and Clinical therapy. Conclusion: Although the number of TAO publications has fluctuated over the past 20 years, it has generally shown a steady upward trend. Etiology and treatment research on TAO and some keywords such as trail, therapy, outcome, management, stem cells, angioplasty, and activation will become a hot spot in the future.

A modified pixel value ratio based on contralateral normal bone: a novel reliable indicator for distraction osteogenesis.

BACKGROUND: The traditional pixel value ratio (tPVR) is subject to disuse osteopenia of the adjacent bone in distraction osteogenesis (DO). Therefore, a modified PVR (mPVR) based on the contralateral normal bone was developed and validated to address this issue. METHODS: A total of 79 bone lengthening subjects were recruited in this retrospective study. The difference between the mPVR and tPVR of early callus was identified in the first three months after osteotomy. Moreover, we further investigated the relationship between mPVR and healing index (HI), lengthening index (LI) and external fixator index (EFI). Finally, the potential influencing factors for mPVR of the early callus were analyzed. RESULTS: The mPVR was significantly lower than the tPVR in the first three months after osteotomy, and the difference gradually increased. Interestingly, the mPVR of the early callus in the first two months was negatively correlated with the HI, LI and EFI. Moreover, the age, lengthening site, total bilirubin and mean hemoglobin content were associated with the mPVR of early callus during DO. CONCLUSION: The mPVR based on contralateral normal bone is a novel reliable indicator for DO, which may be helpful for the clinical management of DO. However, the findings of this study need to be confirmed further by larger prospective research.

The early posterior cortex pixel value ratio: a novel reliable indicator for distraction osteogenesis.

Aims: We aimed to explore the associations of the early PVR in four cortices with Healing Index (HI), Lengthening Index (LI), and External Fixator Index (EFI) in the bone union and non-union groups. Methods: A total of 52 patients, including 39 bone union and 13 bone non-union subjects, were recruited in this study. The general characteristics and PVR in four cortices in each group were explored. Afterward, the early PVR in four cortices, including medial, lateral, anterior, and posterior sides, were compared. Finally, the associations of the early PVR in four cortices with HI, LI, and EFI were also investigated. Results: The general characteristics of these patients were consistent, except for HI (31.54 ± 12.24 vs. 45.08 ± 27.10, P = 0.018) and EFI (57.63 ± 18.15 vs. 71.29 ± 24.60, P = 0.046). The growth of regenerated callus was asymmetrical in the bone union group (the posterior PVR seems to grow faster), whereas no statistical difference was obtained in the bone non-union group. Furthermore, the posterior PVR in the bone union group was significantly higher than that in the bone non-union group (the first month: 0.96 ± 0.17 vs. 0.86 ± 0.06, p = 0.047; the second month: 0.98 ± 0.14 vs. 0.89 ± 0.09, p = 0.041; the third month: 1.00 ± 0.12 vs. 0.92 ± 0.09, p = 0.039). Most importantly, the posterior PVR was inversely associated with HI, LI, and EFI (the first month: r = -0.343, p = 0.041; r = -0.346, p = 0.042; r = -0.352, p = 0.041; the second month: r = -0.459, p = 0.004; r = -0.277, p = 0.101; r = -0.511, p = 0.002; the third month: r = -0.479, p = 0.003; r = -0.398, p = 0.018; r = -0.551, p = 0.001) in the bone union group, respectively. However, this finding was lost in the bone non-union group. Conclusion: The early posterior cortex PVR seems to grow faster than the medial, lateral, and anterior sides in the bone union group, which represents an asymmetrical development pattern. Moreover, the posterior cortex PVR was negatively associated with HI, LI, and EFI, respectively. The posterior cortex PVR may be a novel and reliable detection index in the process of DO.

Global trends in poliomyelitis research over the past 20 years: A bibliometric analysis.

Poliomyelitis is an acute infectious disease caused by poliovirus. This bibliometric analysis aims to examine the status of poliomyelitis research in the past 20 years. Information regarding polio research was obtained from the Web of Science Core Collection database. CiteSpace, VOSviewer, and Excel were used to perform visual and bibliometric analysis with respect to countries/regions, institutions, authors, journals and keywords. A total of 5,335 publications on poliomyelitis were published from 2002 to 2021. The USA was the county with the majority of publications. Additionally, the most productive institution was the Centers for Disease Control and Prevention. Sutter, RW produced the most papers and had the most co-citations. Vaccine was the journal with the most polio-related publications and citations. The most common keywords were mainly about polio immunology research ("polio," "immunization," "children," "eradication" and "vaccine"). Our study is helpful for identifying research hotspots and providing direction for future research on poliomyelitis.

Global trends and current status of amputation: Bibliometrics and visual analysis of publications from 1999 to 2021.

OBJECTIVE: To generalize the research status, hotspots, and development trends of amputation-related research. METHODS: The data from 1999 to 2021 were collected from the Web of Science core collection database, and analyzed through bibliometrics software (CiteSpace and VOSviewer) for the dual-map overlay of journals, top 25 references with the strongest citation bursts, top 25 keywords with the strongest citation bursts, and timeline of keywords. RESULTS: A total of 8,588 literature studies were involved in this study. The United States ranks the first in terms of H-index, total number of publications, and total citations. US Department of Veterans Affairs, Veterans Health Administration, and University of Washington are the major contributors to amputation. Prosthetics and Orthotics International, Archives of Physical Medicine and Rehabilitation, and Journal of Rehabilitation Research and Development are the main publication channels for articles related to amputation. Geertzen JHB, Czerniecki J, and Dijkstra PU are major contributors to amputation. In addition, research on limb salvage treatment and surgical methods for amputation will become a hotspot in the future. CONCLUSION: The total number of publications for amputation has generally increased from 1999 to 2021. Our study is beneficial for scientists to specify the research hotspot and development direction of amputation.

The role of cellular immunity in influenza H1N1 population dynamics.

BACKGROUND: Pre-existing cellular immunity has been recognized as one of the key factors in determining the outcome of influenza infection by reducing the likelihood of clinical disease and mitigates illness. Whether, and to what extent, the effect of this self-protective mechanism can be captured in the population dynamics of an influenza epidemic has not been addressed. METHODS: We applied previous findings regarding T-cell cross-reactivity between the 2009 pandemic H1N1 strain and seasonal H1N1 strains to investigate the possible changes in the magnitude and peak time of the epidemic. Continuous Monte-Carlo Markov Chain (MCMC) model was employed to simulate the role of pre-existing immunity on the dynamical behavior of epidemic peak. RESULTS: From the MCMC model simulations, we observed that, as the size of subpopulation with partially effective pre-existing immunity increases, the mean magnitude of the epidemic peak decreases, while the mean time to reach the peak increases. However, the corresponding ranges of these variations are relatively small. CONCLUSIONS: Our study concludes that the effective role of pre-existing immunity in alleviating disease outcomes (e.g., hospitalization) of novel influenza virus remains largely undetectable in population dynamics of an epidemic. The model outcome suggests that rapid clinical investigations on T-cell assays remain crucial for determining the protection level conferred by pre-existing cellular responses in the face of an emerging influenza virus.